<template>
  <span>
    <input
      class="input-file"
      type="file"
      accept=".csv, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.ms-excel"
      style="display: none"
      @change="exportData"
    >
    <el-button type="primary" icon="el-icon-upload" size="mini" @click="btnClick">{{ fileName }}</el-button>
  </span>
</template>
<script>
import XLSX from "xlsx";
export default {
  name: "ImportExcel",
  props: {
    fileName: {
      type: String,
      default: function() {
        return "导入EXCEL";
      }
    }
  },
  data() {
    return {};
  },
  methods: {
    btnClick() {
      document.querySelector(".input-file").click();
    },
    exportData(event) {
      if (!event.currentTarget.files.length) {
        return;
      }
      const loading = this.$loading({
        lock: true,
        text: "Loading",
        spinner: "el-icon-loading",
        background: "rgba(0, 0, 0, 0.7)"
      });
      const that = this;
      // 拿取文件对象
      var f = event.currentTarget.files[0];
      // 用FileReader来读取
      var reader = new FileReader();
      // 重写FileReader上的readAsBinaryString方法
      FileReader.prototype.readAsBinaryString = function(f) {
        var binary = "";
        var wb; // 读取完成的数据
        var outdata = {}; // 你需要的数据
        var reader = new FileReader();
        reader.onload = function(e) {
          // 读取成Uint8Array，再转换为Unicode编码（Unicode占两个字节）
          var bytes = new Uint8Array(reader.result);
          var length = bytes.byteLength;
          for (var i = 0; i < length; i++) {
            binary += String.fromCharCode(bytes[i]);
          }
          // 接下来就是xlsx了，具体可看api
          wb = XLSX.read(binary, {
            type: "binary"
          });
          for (var j = 0; j < wb.SheetNames.length; j++) {
            outdata[wb.SheetNames[j]] = XLSX.utils.sheet_to_json(
              wb.Sheets[wb.SheetNames[j]]
            );
          }
          // outdata = XLSX.utils.sheet_to_json(wb.Sheets[wb.SheetNames[0]])
          // 自定义方法向父组件传递数据
          // console.log('outdata = ' +
          loading.close();
          that.$emit("getResult", outdata);
        };
        reader.readAsArrayBuffer(f);
      };
      reader.readAsBinaryString(f);
    }
  }
};
</script>
